Punch and die set



Feb. 5, 1952 J, w, BARNETT 2,584,415

PUNCH AND DIE SET Filed Jan. 15, 1947 y 3 sheets-sheet 1 ZELE- 1 'JOHN W. BARETT A r rma/ws",l

Feb. 5, 1952 J. w. BARNETT PUNCH AND DIE SET Filed Jan. 15, 1947 sheets-sheet 2 INVENTOR. Jol-1N W. BARNETT A Trae/usr I Feb 5, 1952 J. w. BARNETT 2,584,415

PUNCH AND DIE 'SET Filed Jan. 15, 1947 l 5 sheets-sheet s Ema-. LJ.

Bz E 77 64 IN VEN TOR.

' JOHN W. BARNETT 'IIA Y BY Arron/Vey Patented Feb. 5, 1952 UNITED 1 STATES@ ATENT oFFICE The present invention relates to a punch and die set including a removable and replaceable punch construction and a quick-change stripper plate. v

It is conventional practice in sheet metal stamping to mount a Vstripper plate and punch to a punchretaining plate and then to rigidly bolt the latter to an upper die shoe member in accurate alignment with respect to the die. Whenever it is necessary to remove or replace the punch, the entire punch retaining plate assembly must be disassembled and the accurate alignment thereof is impaired.V Not only is considerable time consumed in removing the punch retaining plate from the die shoe and in realigning it whenever a punch is replaced, but each succeeding realignment becomes increasingly diflicult as a result of wear between the parts involved during each dismantling. Similarly, conventional practice frequently requires the removalof the punch and die from the press in order to remove the stripper plate. This operation is costly in itself and further shortens the life of both the die and the punches.

Accordingly, one of the principal objects ofthe present invention is toprovide an improved punch and. die set having a simplified and economically manufactured mounting between the punch retaining plate and both the stripper and punch, permitting attachment or removal of` these for repair or replacement without necessitating the removal o f the punch retaining plate or disturbing its accurate alignment with respect to the die. and further permitting removal of the stripper plate without necessitating thef removal of the punch and die from the press. ,Y f

In order to hold the punch holder in proper alignment within the punch retaining plate, it is also conventional Yto utilize spring pressed ball bearings partially set within a recess in both the punch holderand punch retaining plate, or to utilize tapered wedges pressed against corresponding tapered portions of the punch holder and held in position by screws or resilient means. Such devices are frequently intricate and complicated by a complexity of partswhich are expensive to manufacture, are `time-consuming in their assembly, and require special-tools for their operation. liurthermorawherev steel ball bearings are keyed partially in bothv the punch or punch holder 4and punch retaining plate, the relatively soft metal of the punch holder and punch retaining plate as compared to the hard metal of the bearing soon results in excessively worn fittings, especially during heavy stamping, permitting misalignment of the punch and requiring its early replacement. Such practices also frequently fail to provide the adequate support required to hold the punch during heavy stamping operations.

Accordingly, other important objects of the present invention are to provide an improved punch and supporting means therefor having a simplified, economical and readily applied means for detachably securing the punch and its sup'- porting means tothe punch retaining plate without removing the latter or disturbing its alignment with the die, which may be suitably but not exclusively adapted for use with the aforementioned punch and die set, which may be adapted to provide adequate positive support for multiple or intricate punches to assure proper alignment thereof during stamping operations, and which may be particularly adapted to withstand the forces of heavy punching and stripping. y

In certain preferred embodiments of the present invention, it is desirable to utilize punch holders having flanges or,extending lugs to hold the punch holder within the punch retaining plate, especially during the stripping operation. During heavy stamping, there is frequently a tendency for the flanges or extending lugs to weaken and shear from the punch holder as a result of repeated impacts against the body of the punch retaining plate.

Accordingly, another important object of the present invention is to provide, in a punch holder having anges or extending lugs which hold the punch holder within the punch retaining plate, an improved means for mounting said punch holder within the punch retaining plate so as to avoid shearing of said flanges or extending lugs -under the impact of heavy stamping.

Other objects of this invention will appear in the following description and appended claims, reference being had to the accompanying drawings forrning a part of this specification wherein like reference characters designate corresponding parts in the several views.

In the drawings:

Fig. 1 is a plan elevation of a sheet metal punch and die set embodying the present invention.

Fig. 2 is a vertical section through the die set and punch holder of Fig. 1, taken in the direction of the arrows essentially along the line 2-2 of Fig. 1 and showing the stripper plate retaining screw and lug nut.

Fig. 3 is a fragmentary enlarged horizontal section through the punch holder, taken in the direction of the arrows essentially along the line S--S of Fig. 2.

Fig. 4 is a fragmentary enlarged horizontal section through the punch holder, taken in the direction of the arrows essentially along the line -ii of Fig.- 2l

Fig. 5 is a fragmentary vertical section through a punch retaining plate and punch holder assembly, showing a modified form of punch holder,l similar to that of Fig. 2, but being adapted for multiple punches.

Fig. 6 is a fragmentary horizontal section through the punch holder of Fig. 5,7`ta'ken in the direction of the arrows essentially along the line of Fig. 5. y

Fig. 7 is a fragmentary horizontal section through they punch holder of Fig. 5, taken in the direction of the arrows essentially alohg the line 'iil'o'f Fig.`5.

` Fig. t` isk aside elevation ,or a, 'modified form or punch particularly adapted o'ij heavy punciigh thev lugl 'r''ut `land stripper plate retaining screw of Fig. l, tal-lier;k the direction of the arrows essentially along the line Hr-l of Fig. 2.

and also' adapted for use interchangeably, w li thetyfpej'or punch andipunch'holder shown entary horizontal sectionV g corresponding plurality of sleeves 24 provided by the upper die shoe member 2|). The punch retainingplate 25 is spaced from the upper die shoe member 20 by the hardened abutment plate and both aresecured to the upper die shoe member 2B by the plurality of cap screws 21. lhere desirable dowel pins may be utilized to join and to facilitate the alignment between the upper die shoe member 20 and punch retaining plate 25.

A particular punch holder embodying the present invention is shown by way of example in Figs. 1 through 4. A cylindrical punch holder 23 provides, the, pair ofg diametrically opposed radially extending retaining lugs 29 at its butt VVend, Fig. 3, the coaxially extending punch opening 33 for the punch shank 3|, and a tapered Fig/11 is a fragmentary 'vertical section Y through the' upper po,V Y mentor a. die set, snowing amodine'rd punch and purfloli retaining plate` particularly adapted for heavy' punching. Y

Fig. '12 is a fragmentary enlarge-iv horizontal section through thepuiio'n of gigli, taken is the' direction of the 'arrows' essentially along the unee242otitis.1i.V e Y Fig. i3. is a fragmentary enlarged horizontal section tlirigh the 'punch of Fig.. ll, taken in the direction fp'r'therllvs' essentially along the line Fig. liis side elevation of a modification o the .punch shown in Fig'. l1.`

Before explaining the. present invention in detail 'it i's` to be understood 'that the invention is not limited in its application to. the details of construction and arrangement of parts illustrated in the accompanying drawings, since the inventionis capabler or. other embodiments and of being practiced orcaiied out in various ways. Also it istobe understood 'that the phras'eolg'y or terminology employed herein is ior Athe "purpose of description and not of limitation.

Referring to the drawings, Figs. l and 2 'shout' or vertical guideV pins 23, seeuredin the lower die shoe member 22 to serve as g'iiides for the ori of another ein'bodie Y the The,

of the punch shank 3 I YIn the course" of normal sheet metal stamping or punching, itisfreouently necessary to remove the punch from its mounting within the die set for repair or replacement. In conventional mountings, removal of the punch 3| necessitates tned-smantiingofl 'a consider-able' portion of the die assembly, inelldng theremoval ofthe punch retaining plate 125 from the upper die shoe member 2E?. Thus upon replacement of the punch 3|, considerable time required'to realign the plate with the other members of 'thedie set, 'para tiouiarly' the button die 34- which is shown mounted within the lower die shoe member 22 by way Iof example' of a specific application ofY the present invention; Y

order to permit repla'cementoilthe punch 3| without disturbing the alignment of the punch Vretainiriig plate 25,- a counterboredpunch holder opening 35 isprovided in the plate 25 for the punchl holder 28;y Thecounterbored upper portion of the openng 35- adjacentV the hardened abutment plate Zgecmprises the coaxial annular recess 351er the retaining lugs 29. Also opening into the opening 35 andthe annular recess 361 are theY two axiall'y extending' diametric'ally op'- po'sed lug receiving passageways 3T andz38l within the punch retaining plate 25 and mating with the igs 29 toV permit`pa's'sag'e: thereof to. theV recess When the lugs 29 enter the annular recess 3E, theyJ may be moved. out of' alignment with the -passageways 37 and 38 byrotation of the punch holder 28. Key 39'` may then-be inserted into the.

shown, on the retraction stroke of a stampingv operation; @ne orv a plurality of lugs 29-m`ay be utilized, but I have'preferred to use-two diametrically opposed lugs so asf to balancethe forceson the punch holder 28 during stripping. A single large lug will obviously provide the same resistance to shearing as provided by two smaller lugs, but in the use of' a single large l-ug', the relatively wide passageway for the wide lug, corresponding in function to the passageways 3`|iandy 33, presents a relatively large break in the supporting wall of the punch holder opening 35 and results in a tendency for Ythe puh'h holder 28 to' stripping. By utilizingtwo lugsY 29 Vas described.

e'aonvof "naifl the width required 'by 'a single llug toprovide the same shear strength, the break at any one location inthe supporting wall of the punch holder opening 35 will be correspondingly reduced by one-half, and the shearing forces of stripping will also be balanced on opposite sides of the punch holder 28.

Various convenient devices may be employed to hold the key 39 in its proper place within the passage 31 and the annular recess 36. In the preferred embodiment of the invention shown, the key 39 is held in position by the C-shaped snap spring 40 which seats within the annular groove or seat 4|, provided by the punch holder 28, Figs. 2 and 4, and underlies a portion of the key 39.

It is apparent from the foregoing that the punch 3| may be readily removed from its mounting upon spreading the C-shaped spring 4B and removing it from its seat 4|. The key 39 may then be moved from the passageway 31, permitting alignment of the lugs 29 with their respective passageways 31 and 38. In this position the punch holder 28 may be readily removed from the lower portion of the punch retaining plate without in any way disturbing the alignment of the plate 25, permitting the punch 3| to be simply removed from the opening 30. Means, as for example a recess in the end of the key 39,. may be provided where desired or required to facilitate removal of the key 39 from the passageway 31. By reversing the above procedure, the punch 3| may be readily remounted within the die assembly. The alignment of the punch 3| with the die 34 will be assured because the alignment of the punch retaining plate is not disturbed.

One problem in sheet metal stamping involving intricate or multiple punches has been to provide means for holding the punch in positive alignment with respect to the punch retaining plate during heavy punching or throughout long periods of repeated punching operations. By means ci a simple adaptation of the present invention, Figs. 5, 6 and 7, a punch holder similar to the punch holder 28of Fig. 2 may be used to hold intricate or multiple punches in positive alignment.

Fig. 5 is a fragmentary vertical section through portions of the upper die shoe member 2t and hardened abutment plate 26 to'which a punch retaining plate 25A is secured, as in Fig. 2, by bolts, not shown. The essential function and arrangement of the parts shown are similar to those discussed above, but with modifications which are noted below. The punch holder 28A provides the lugs 29A and the plurality of countersunk openings 30A for the plurality of punches 3|A, each of which has a tapered head 33A. The counterbored punch holder opening A is provided for the punch holder 28A. The counterbored portion of the opening 35A comprises the recess 36A which provides a runway for the lugs 29A. Lug passageways 31A and 38A are provided in the punch retaining plate 25A to receive the lugs 29A and to permit axial movement of the punch holder 28A. In addition, an axially extending keyway 42 is provided in the periphery of the punch holder 28A and is so positioned that when the punches 3| A are properly aligned with respect to the other die members, the keyway 42 will be aligned with one of the said axially extending passageways, 31A for example, to provide a keyway for the key 39A which is adapted to jointly fill both the keyway 42 and passageway 31A. 'Y The key 39A is heldv in position by the C- shapedspring 40A; seatedvwithin the `annularV the removaLor replacement ofthe punches 3| A' from their ,mountinga may be accomplished essentially as described in connection with the application of the punch 3| and punch holder 28 of Figs. 1 through 4. j Y

In the discussion above, both the single punch holder 28 and multiple punch holder 28A have been-separable from their punches. For certain purposes, particularly for heavy punching, it is feasible for the punch and punch holder to comprise a unitary structure as shown by the punch 43 yof Figs. 8 and 9. In this instance, the punch 43 provides the diametrlcally opposed radially extending retaining lugs 45 at the butt end thereof, the annular groove 41 for a C-shaped key retaining spring, and the round punching surface 44. In application, the punch 43 is utilized similarly to the punch and punch holder combinations of Figs. 1 through 1. The chief distinction is that the punch 43 and its punching element 44 are not separable. If for any reason it is desirable to utilize this type of punch with a punching surface that is not round, proper alignment of the punch 43 within its punch retaining plate may be maintained by keying the punch 43 to its punch retaining plate in the manner similar to that disclosed in Figs. 5, 6 and 7.

In many sheet metal stamping processes, it is necessary to employ a spring pressed stripper platenmounted for vertical movement relative to the sheet metal workpiece so as to engage and press the workpiece against portions of the die during the punching and stripping operations. Itis commonly most feasible to space the stripper plate from the underside of the punch retaining plate by a resilient mounting thereto so as to permit vertical movement between the stripper plate and the punch retaining plate. Accordingly, removal of the punch. retaining plate for replacement of a punch also necessitates removal of vthe stripper plate. f

In order to realize the Voptimum advantage of the quick-change replaceable punches and punch holders ofthe present invention, it is important to provide means for easily and quickly removing the stripper plate assembly from the punch retaining plate without disturbing the alignment of the latter with the die or without removing the die from the press. This is accomplished by the present invention with the stripper plate 48, Figs. 2 and 1G, which provides the plurality or counterbored openings 49 for the corresponding plurality of socket-headed screws 58. Each screw 50 provides a threaded portion 5| for screw-threaded engagement with a lug nut 52 and the lock nut 52A. The lug nut 52 carries the radially extending lug 53 and is verticall.7 movable `with the screw 5D within the grooved Well 54provided therefor in the punch retaining plate 25 and having the radially extending groove 55 for the lug 53. The lock nut 52A is screwed tightly against the upper surface of the stripper plate 48 to prevent screw 5U from falling coinpletely out of the stripper plate 48 in the event that screw 50 should accidentally become looscned-'from lug nut 52.

Each Iwell 54 and groove 55 opens through the top o'i the punch retaining plate 25 to permit insertion of the corresponding lug nut 52 therein before the plate 251s initially aligned in position and Secured t0 thecupperf.die.shoe member 2D.

Each stripper screwl I! may their enterI the co1?- respondingv well 54 from Abelovv through the open-E ing 56 provided thereforV in the punch retaining plate at thev base o1" each well 54. With the lug S34-within its groove 55, thelug nut. v52 is--pre vented from turningv when theV` screw 1s screwed thereto.

As in conventional practice, the stripper plate 48 is spaced from the punch retainingplate by theplurality or compressed springs 51; each` of which seats at opposite* ends in seats 58- and 59 provided bythe stripper plate 48 and punch retaining plate 25, respectively; The stripper plate 4B may move verticallywith respect'to the plate 25 by means ofthe sliding screws 50 which move within theV wells: 54 during;Y the stamping operation.

In application,- the quick-change V stripper plate 48 maybe detachably secured-to'thetpunch retaining plate- 25 without-disturbingl the, alignment of the latter with respect to the diev 34, merely by inserting the springs, 51 within their respective seats 58 andY 59 andby screwing the socket-headed screws-50 into their respective lug nuts 52. The operation is facilitated by the plurality of horizontal pinholes 5I. one'of each leading from the exterioror the` punch retaining plate 25 to the interior of one of each of'the wells 54 just above the top o the lugnut 52 therein when the latter isrin aloweredposition ff i A pin may thus be inserted'into the pinhole 5i above the lugnut` 52 to prevent the latter-V from moving upward when the socket-headed screw 50' is screwed thereto. A pin may also be` infserted into the pinhole El under thelug 52, when 11i the latter is raised above the'pinhole 6I, so as to hold the stripper plate 48 against the oon1- pression of the springs 51 and to project the endof the punch 3| through punch hole62 provided therefor in the stripper plate 48-. 'I hus proper alignment of the punch 3| with the die Mis` also facilitated.

Other means withinthe spirit or my Vinvention for detachably coupling the screws 53,to the quick-change stripper plate 48 will suggest themselves to the skilled mechanic. The lug'nut 52 may be provided as the head of the screw' 50, for*v example, which in that case would be threaded at its lower end and detachably secured' to the stripper 48 by a nut which would replace the socket head of the screw presently employed.. Also, for particular requirements,A the grooved well 54 may be` adapted for modified lug nuts having a plurality of lugs rather than the single lug 53 shown. Where desirable or necessary for particular requirements, alignment studs maybe projected downward from the plate 25 and slidably passed through bushings within the` stripper 43 to afford additional support and' to- Y assure proper alignment betweenthe `stripper 48 and punch retaining `plate 25.

Figs. 1l, 12 and 13 show another embodiment of the present invention which provides a readily replaceable punch particularly vadapted forA usewith heavy punching or stripping. Fig. 11 is a fragmentary vertical section,v similarV to Fig. 5', through a portion-of the upper die shoe member et, the hardened abutment plate 66, and punch` retaining plate 61, all of which correspondY in structure and function to the upper` die `shoe member 2G, hardened abutment plate 26, and the punch retaining plate 25A, respectively, of 5.

The punch retaining plateA 61 suitably bolted to the abutment plate- 66 andthe upper die*` shoey member by means not-shown.

The punch comprises the cylindrical body 59, the butt end 1t, punching end 1|, the annular ree taining proje'ction12v spaced between the punch? ing yend 1| and abutmentV end 10V so that the distance between the butt end 1.0 andthe lower face of the projection 12 is equal to the thiclzzness of the @punch retaining plate 61', and the. axially extending keyway 13.within the annularprojection 12, Figs.v 12 and-13. The punch retaining plate 61 provides the counterbored punch receivingopening'M `for the'butt end of the punchiiV and has` the counterbored portion 15 for the Vannuiarprojection 12.

In application, the preach` is inserted' intoV the -counterbored opening 14 with its butt. end 1B vresting against the hardened abutment plate 66 and with the lower surface of the annular projection 12'ush with the lowerY face of' the punch retainingplate 61. In this position, the, capping plate 15 may be rigidly secured to the punch, retaining plate 'l' by the plurality of screws 11,y with the punching end 1! penetrating the punch opening 13 provided thereforA in the capping plate 15. By aligning the axially extending keyway 12, which is adjacent the punch opening sii in the capping plate Figc'. 1?., with the heya/ay 53, the keyv t may be inserted jointly with-in both keyways 13 and le tc positively lcclethe punch body @t in prop-er alignment'within thepunch 'ning plate E?. I

Similarly tc the inanner in whichA the aforementioned izeys 39 and 39A are detachably se.

mired` in position, the C-shaped key retaining]Y plate is nate it achieved. by means or a plurality of ralignmentdowel pins 33 imbedded. within the upperdie shoe member 35 and. projected-downward through the abutment plate et and the punch retaining plate 1 to iit into thecorresponding plurality of alignment holes 811 provided therefor. in the capping` plate 15. Y

Obviously, the provision for holdingY the punch body Sein proper alignment is only required;l for multiple or intricate punches, as in the case of.

the square punching surface 'i! ig. 13%, Referring to Fig. 14, wherein the punch 553A has the Y circular punching surfacel'iA, theannular rctainingr projection 12A needinot be provided with a keyway correspondingto the llzeyvvay-13.` However inV both thev punch or Figs. 1l, 12 and 13 and the punch of.. Fig. 14, the annularretaining projections 12 and 12A, respectively, provideV optimum supp-ort to prevent the punch-B9 or Et as the case may be, from pulling through the punch openingsuch as 13', Eig. 1l, during heavy stripping. The.projectionslzand v12A serve the same function as the aiorementionedlugs tand A, but inthe case ofv the., projections 12 andv 12A, the force oi stripping isdftbuted over a larger area than the areal afforded by the lugs;

2S and 29A. Thusv shearing of the annular projections 12 and 12A duringl heavy stripping` isv avoided.

Theprojections 12 andr12A are further protected` from shearing during the impact of; heavy punching 4by the provision of thespacing Biibef tween the upper portions of thefprojectimsV 12 or 12A and the axially adjacenty portions of. the punch retainingY plate 5 1; By virtue ci, the spacing 85, the impactV of heavy punchingris transmitted directly fromthe punchingendjTli to, the hardened Vabutment plate 66; which is in, direct contact with the'butt 1l).-` No impact can Alignment ci the retainer plate 61.

By the above description andv disclosures, I have provided improvements in die punching apparatus whereby a simplified and economical method of mounting punches and the stripper plate to the punch retaining plate is provided, permitting these parts to be readily removed or replaced without removing the die from press or disturbing the alignment of the punch retaining plate with respect to other portions of the die and4 whereby improved' quick-change punches and punch holders are provided which are-particularly adaptable for use in heavy punching or stripping and which may be adequately supported in positive and accurate alignment within the punch retaining plate.

I claim: l g

1. In a die punching assembly, the combination of a punch having a plurality of radially projecting retaining lugs, a punch retaining plate having a punch opening therein for the body of said punch, an `annular lug receiving recess opening from said punch opening above the lower portion thereof, a plurality of axially extending lug receiving passageways within said punch opening and leading to said annular recess to permit separation of said -punch from said punch retaining plate, means to prevent alignment of said lugs with said lug receiving passageways when`said lugs are within said annular recess and including a key adapted to nt withinl one of said passageways and to project into said annular recess, and means to detachably secure said key Within said axially extending passage- Way therefor. d

2. The combination in a die punching assemybly as claimed in claim 1 and being further characterized in that said means to detachably .secure said key within said axially extending passageway therefor includes an annular groove in the periphery of said punch body at the base of said key and a C-shaped key retaining spring adapted to snap into position within said annular groove and to project beyond the periphery of said punch body to underlie said key. f

3. In a die punching assembly, the combination of a punch holder having a body, a punch opening in said body for a punch shank, a countersunk recess at one end of said punch opening for the head of a punch shank, a plurality of radially projected retaining lugs provided by said body, a'punch retaining plate including a punch holder opening therein for said punch holder, a concentric' annular lug receiving recess opening from said punch holder openingv above the lower portion thereof, and ameans to permit entry of said lugs ,into said annular recess and to permit separation of said punch holder from said punch retaining plate and cornprising a plurality of axially extending lug receiving passageways in said punch holder and leading to said annular recess, means toprevent alignment of said lugs with said passageways' when said lugs are within said annular recess `:and including a key adapted to t 'within one;

of said passageways and to project into said annular recess, and means to detachably securesaid key within the axially extending passage- Way therefor.

4. The combination in a die punching assembly as claimed in claim 3 and being further characterized in that said means to detachably secure said keyV within the axially extending passageway therefor includes an annular groove in the periphery of said punch holder body at the base of said key and a C-shaped key retaining spring adapted to snap into position within said annular groove and to project beyond the periphery of said punch holder body to underlie said key.

5. In a die punching assembly, the combination of a punch having a plurality of radially projecting retaining lugs, an axially extending peripheral keyway within said punch, a punch retaining plate having a punch opening therein for said punch, a concentric annular lug receiving recess opening from said punch opening above the lower portion thereof, a plurality of axially extending lug receiving passageways opening from said punch opening and leading to said annular recess to permit said punch to be detachably mounted with said punch retaining plate, means to hold saidpunch in positive alignment with respect to said punch retaining plate when said lugs are within said annular recess and including a key adapted to fit jointly within said keyway and in one of said axially extending passageways, and means to detachably secure said key within said keyway and the axially extending passageway therefor.

6. In a die punching assembly, the combination of a punch holder, a punch opening in said punch holder for a punch shank, a countersunk recess at one end-of said punch opening for the head holder, a punch retaining plate having a punch holder opening therein for said punch holder, a concentric 'annular lug receiving recess opening from said punch holder opening above the lower portion thereof, a plurality of axially extending lug receiving passageways opening from said punch holder opening and leading to said annular recess to permit said punch holder to be detachably mounted with said punch retaining plate, means to hold said punch holder in posil' tive alignment with respect to saidr punch retaining plate when said lugs are within said annular recess and including a key adapted to nt jointly within said keyway and in one of vsaid axially extending passageways, and means to detachably secure said key Within said keyway and the axially extending passageway therefor.

7. In a punch adapted for use with a punch retaining plate having a punch receivingopening, a concentric annular lug receiving recess opening from said punch receiving opening, and a plurality of axially extending lug receiving passageways opening from said punchV holder opening and rleading to said annular recess, the combination of a punch body, a punching end of said body, a plurality of radially extending retaining lugs provided by said body, and an annular groove in the periphery of said body and axially spaced from said lugs to receive a C- shaped key retaining spring.

8. The combination in a punch as claimed in claim 7 and being further characterized in that means are provided to hold said punch in positive alignment with its punch retaining plate and including an axially extending keyway Within said punch body.

9. In a punch retaining plate, rigidly alignable with the die, and a punch adapted for heavy punching and replaceably mountable with said punch retaining plate without disturbing the alignment thereof with respect to said die, the

11 combination oi' a punch body for saidpunch, a butt end and a punching end of said body, an annular retaining projection provided by said body, a counter-bored opening in said punch retaining plate and adapted to receive the butt end and annular retaining projection of said punch, .a capping plate detachably secured to said punch retaining plate and having an opening penetrated by the punching end of said punch body,

said punch being prevented from pulling vout of said punch retaining plate during stripping by contact between said annular retaining projection and said capping plate.

1G. The combination as claimed in claim 9 and being further characterized in that -mea-ns are provided to securely hold said punch in positive alignment with respect to said punch .retaining plate and including a keyway in said capping plate, a keyway within said punch, ,a key adapted for insertion jointly within bothI of said keyways, and means to detachably secure said key in position jointly within both of said keyways.

ll. A combination as claimed in claim 9 and being further characterized in that means are provided to prevent shearing of said annular retaining projection by impact thereof against said punch retaining plate during heavy punching and including a spacing maintained between said annular retaining projection and the axially adjacent portion of said punch retaining plate;`

i2. In a punch for heavy diestarnping and adapted te be detachably mounted with a punch retaining plate having a counterbored punch receiving opening and to bev detachably secured in an operative position bymeans of a capping plate which is detachably secured to `said punch retaining plateand which also provides a punch receiving opening, the combination of a punch body having a punching end adapted to penetrate the punch receiving opening of said capping plate when the latter is operatively secured to said punch retaining' plate, and an annular retaining projection of said body and adapted for insertion into the counterbored punch receiving opening of said punch retaining plate so as to prevent removal of said punch therefrom when said capping plate is operatively secured to said punch retaining plate.

13. In a punch for heavy die stamping and adapted to be detachably mounted with a punch retaining plate having a counterbored punch receiving opening and to be detachably secured in an operative position by lmeans of a capping plate which is detachably secured to said punch .retaining plate and which also provides a punch receiving opening, the combination of a punch body having a punching end adapted to penetrate the punch receiving opening of said capping plate when the latter is operatively secured Yto said punch retaining plate, an annular retaining pro- .iection of said body and adapted for insertion` into the punch receiving opening of said punch retaining plate, and an axially extending keyway in said punch, said punch being thereby adapted for detachably mounting with said punch retaining plate without disturbing the alignment thereof with its die shoe upon removal of said capping pla e.

14. In a die stamping assembly adapted to permit ready replacement of the punching element and having a stripper plate depended from a punch retaining plate in variable spaced relationship therewith, the combination of a well having an opening in the upper surface of Said punch retaining platep a ishaft opening leading to the base of said well .from the underside of said punch retaining plate, a stripper plate supporting shaft slidable within said shaft opening, an enlarged lie'ad vof said stripperplate supporting shaftslidable within said well, means to detachably secure-said stripper A,plate to the depending portion *ofA said stripper plate supporting shaft, a punch holder, a punch opening in said punch holder for a punch shank, a countersunk recess at one end of said-punch opening for the head of a punch shank, a plurality of radially projected retaining lugs provided by said punch holder, a punch holder vopening in said punch retaining plate for said punch holder, a concentric annular lug receiving recess opening from said punch holder .opening above the lower portion thereof, a means to permit said punch holder to be detachably mounted with said punch lretaining plate and comprising a plurality of axially extending lug receiving passageways in said punch holder opening and leading to said annular recess, meansto prevent alignment of said lugs with 4said passageways whensaid lugs are within said annular recess and including a key adapted to nt within one of said passageways and to `project into .said annular recess, and means to detachably secure said key within the axially extending passageway therefor.

15. In a die stamping assembly adapted to permitready replacement of the punching element and having'a stripper plate depended from a punch vretaining plate in variable spaced rela- .tionship therewith, the combination of a punch holden-a, punch openingin said punch holder for a punch shank, a countersunk recess at one end of said punch opening for the head of a punch shank, a :plurality of radially projected retaining lugs provided by said punch holder, a punch holder opening in said punch retaining plate for said punch holder, a concentric annular lug receiving recess opening from said punch holder opening above the lower portion thereof, a means to `permit entry of said lugs into said annular recess and to permit separation of said punch holder from said punch-retaining plate and comprising a plurality of axially extending lug receiving passageways in said lpunch holder and leading to said annular recess, means to prevent alignment of said lugs with said passageways when said lugs are within said annular recess and including a key adapted to t within one of said passageway's and toproject into said annular recess, means toV detachably secure said `key within the axially extending passageway therefor,v a well having an opening in the upper surface of said punch rvretainingr plate, a shaft openingv leading to the base of said well from the underside of said punch retaining plate, a stripper plate supporting shaft slidable within said shaft opening, an enlarged head of said stripper plate 'supporting :shaft slidable within said well, and means to detachably secure said stripper plate to the depending portion of said stripper plate supporting shaft.

16. In a die .stamping assembly having a stripper plate dependent froma punch retaining plate in a variable spaced relationship therewith and replaceably mountable thereto without disturbing the alignment thereof with respect to the die, the combination of a vertical well having an opening in the upper surface of said punch retaining plate, ashaft opening leading to the base ofsaid well from .the underside of said punch retaining Plate, e, stripper plate supporting shaft i 13 slidable within said shaft opening, an enlarged head of said stripper plate supporting shaft slidable within said Well, said punch retaining plate having a pin hole extending from the outer surface thereof to the interior of said well above the enlarged head of said stripper plate supporting shaft when said head is in a lowered position Within said Well, and means to detachably secure said stripper plate to the depending portion of said stripper plate supporting shaft.

JOHN WILBUR B'ARNETT.

REFERENCES CITED The following references are of reeord in the rile of this patent:

Number 14 UNITED STATES PATENTS Name Date Wagenen Oct. 25, 'i892 Tobeler Sept. 4, 1928 Henricson Aug. 6, 1929 Valentine June 24, 1939 Wales Aug. 8, 1939 Baumbach Mar. 1B, 1941 Brooks Oct. 9, 1945 Whistler Oct. 16, i945 

